Method and system for session admission control in broadband wireless network

ABSTRACT

A method and system for providing session admission control for a new session in a broadband wireless network is provided. The method may include obtaining a guaranteed bit rate and a first quality of service class indicator for the new session. The method may further include calculating an available capacity using the guaranteed bit rate and determining whether the available capacity is a negative or a positive value. The new session may be admitted or rejected based on whether the available capacity is a negative or positive value.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to IndianPatent Application No. 4265/CHE/2012, filed Oct. 12, 2012, and entitled“METHOD AND SYSTEM FOR SESSION ADMISSION CONTROL IN BROADBAND WIRELESSNETWORK.” The aforementioned application is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The disclosure generally relates to wireless networks, and moreparticularly to session admission control in broadband wirelessnetworks.

BACKGROUND

Mobile devices have moved from simple voice communication to performingfunctions traditionally performed by larger devices such as laptops anddesktop computers. Such functions include streaming multimedia content,enabling high definition online gaming, and the like. These functionshave become an integral part of our daily lives, but each of these andother functions enabled by mobile devices multiplies the bandwidthrequired for each user. Therefore, wireless network designs havebuilt-in intelligence to determine how, when, and whether to grantaccess to a given user to connect with the network and begincommunication. This intelligence is sometimes referred to as calladmission control.

An example of a wireless broadband network which has such call admissioncontrol is Long-Term Evolution (LTE). LTE is an end-to-end broadband IPnetwork that aims to provide high sector capacity, scalability, improvedend-user throughputs, and reduced user plane latency, bringingsignificantly improved user experience with full mobility. However, thecapacity of the LTE network is limited. Accordingly, mobile operatorsface a delicate balancing act in trying to manage the high speed datatraffic desired by its users, and maintaining the subscriber's qualityof experience by providing a selective session call admission controlmechanism.

An exemplary call admission control technique is illustrated in U.S.Publication No. 2011/0305137 to Chu et al. The '137 publication suggestsusing policy based admission control for a LTE network shared between apublic safety user class and a consumer user class. However, theapproach suggested by the '137 publication may be either too simplisticto handle complex traffic session admission control needs of modern dayapplications in the LTE network, or may lead to instability oroverloading of the system.

Accordingly, there exists a need for techniques for an improved calladmission control in wireless broadband networks such as LTE.

SUMMARY

According to an exemplary embodiment, a method of providing sessionadmission control for a new session in a broadband wireless network isprovided. The method may include obtaining a guaranteed bit rate and afirst quality of service class indicator for the new session. The methodmay further include calculating an available capacity using theguaranteed bit rate and determining whether the available capacity is anegative or a positive value. The method may further include, inresponse to the available capacity being a negative value, selectivelysearching through existing sessions for a first session to be preempted.The method may further include, in response to the available capacitybeing a positive value, determining a first plurality of sessions fromamong the existing sessions that have the first quality of service classindicator and checking whether performance metrics for the firstplurality of existing sessions satisfy predetermined criteria. Themethod may further include admitting or rejecting the new session.

According to another exemplary embodiment, a system for implementingsession admission control for a new session in a broadband wirelessnetwork is provided. The system may include a hardware processor and amemory storing instructions for execution by the hardware processor. Thehardware processor may be configured by the instructions to obtain aguaranteed bit rate and a first quality of service class indicator forthe new session. The hardware processor may be further configured by theinstructions to calculate an available capacity using the guaranteed bitrate and determine whether the available capacity is a negative or apositive value. The hardware processor may be further configured by theinstructions to selectively search through existing sessions for a firstsession to be preempted if the available capacity is a negative value.The hardware processor may be further configured by the instructions todetermine a first plurality of sessions from among the existing sessionsthat have the first quality of service class indicator and check whetherperformance metrics for the first plurality of existing sessions satisfypredetermined criteria if the available capacity is a positive value.The hardware processor may be further configured by the instructions toadmit or reject the new session.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of thepresent disclosure and together with the description, serve to explainthe principles of the disclosure.

FIG. 1 illustrates an exemplary network architecture for a broadbandwireless network.

FIG. 2 illustrates an exemplary component in a base station thatperforms admission control.

FIG. 3A is an exemplary machine algorithm for call admission control.

FIG. 3B is a continuation of the machine algorithm of FIG. 3A settingforth additional exemplary steps.

FIG. 3C is a further continuation of the machine algorithm of FIG. 3Asetting forth additional exemplary steps.

FIG. 3D is an even further continuation of the machine algorithm of FIG.3A setting forth additional exemplary steps.

FIG. 4A is another exemplary machine algorithm for call admissioncontrol.

FIG. 4B is a continuation of the machine algorithm of FIG. 4A settingforth additional exemplary steps.

FIG. 4C is a further continuation of the machine algorithm of FIG. 4Asetting forth additional exemplary steps.

FIG. 4D is an even further continuation of the machine algorithm of FIG.4A setting forth additional exemplary steps.

FIG. 5A is another exemplary machine algorithm for call admissioncontrol.

FIG. 5B is a continuation of the machine algorithm of FIG. 5A settingforth additional exemplary steps.

FIG. 5C is a further continuation of the machine algorithm of FIG. 5Asetting forth additional exemplary steps.

FIG. 5D is an even further continuation of the machine algorithm of FIG.5A setting forth additional exemplary steps.

FIG. 6A is another exemplary machine algorithm for call admissioncontrol.

FIG. 6B is a continuation of the machine algorithm of FIG. 6A settingforth additional exemplary steps.

FIG. 6C is a further continuation of the machine algorithm of FIG. 6Asetting forth additional exemplary steps.

FIG. 6D is an even further continuation of the machine algorithm of FIG.6A setting forth additional exemplary steps.

DETAILED DESCRIPTION

Now, exemplary embodiments of the present disclosure will be describedwith reference to the accompanying drawings. Wherever possible, the samereference numbers will be used throughout the drawings to refer to thesame or like parts. While exemplary embodiments and features of theinvention are described herein, modifications, adaptations, and otherimplementations are possible, without departing from the spirit andscope of the invention. Accordingly, the following detailed descriptiondoes not limit the invention. Instead, the proper scope of the inventionis defined by the appended claims.

An exemplary high level network 10 depicting a broadband wirelessnetwork architecture is illustrated in FIG. 1. For purposes ofillustration, the network 10 corresponds to an LTE network. However, thedepicted LTE network is merely an exemplary network, and thus it will beunderstood that the teachings of the disclosure could well be extendedto other broadband wireless networks such as WiMax, High Speed PacketAccess (3GPP's HSPA), etc.

In FIG. 1, one or more of LTE user equipments (UE) 14-1, 14-2, and 14-3(hereinafter referred to as UE 14) may communicate wirelessly with anevolved nodeB (eNB) 11 that is an LTE base station. An example of a UEmay be a cell phone, PDA, tablet computer, etc. The eNB 11 maycommunicate with an evolved packet core (EPC) 12 that may include amobility management entity (MME) 13. The functionalities of eNB mayinclude Radio Resource Management (RRM), header compression andencryption of user data stream, packet scheduling and transmission,physical layer processing, etc. The MME may be responsible for EPS(Evolved Packet System) Session Management (ESM), EPS MobilityManagement (EMM), EPS Connection Management (ECM), Ciphering andIntegrity Protection, Inter core network signaling, SAE (SystemArchitecture Evolution) bearer control, Handover, etc. The EPC 12 mayalso include a serving gateway (SGW) (not shown) and packet-data networkgateway (PDN GW) (not shown). The combined functionalities may includeSGW and PDN GW include Lawful Interception, Packet routing andforwarding, Transport Level packet marking in the uplink and thedownlink, Packet filtering, Mobile IP, Policy enforcement, etc.

The admission control from the LTE network infrastructure point of viewcan be broadly categorized as

(1) Initial Random Access admission control at eNB;

(2) UE Signaling session admission control at MME; and

(3) Traffic session admission control at eNB.

Initial Random Access admission control is the first level of admissioncontrol where the eNB 11 may decide whether to initiate a communicationpath with the UE 14. Once this Initial Random Access admission controlis complete, UE 14 may send the next set of signaling messages to theMME 13 via the eNB 11 where UE Signaling session admission control maybe performed based on multiple factors and parameters. Once the MME 13accepts the UE Signaling session admission control, then eNB 11 mayexecute the Traffic session admission control and finally decide whetherto admit the UE 14 for transmitting and receiving traffic through theeNB 11. An effective traffic session admission control executed at theeNB 11 may ensure good traffic data throughput in the network forspecific user applications, along with minimum packet delay and packetloss rate in the air interface (not shown) following the eNB 11.

To provide an improved Traffic session admission control in the eNB 11,an exemplary Improved Traffic Session Admission Control (ITSAC) 15 maybe provided in the eNB 11. While FIG. 1 illustrates that the ITSAC 15may be provided in the eNB 11, ITSAC may be provided separately fromeNB11. An exemplary implementation of the ITSCAC 15 is illustrated inFIG. 2.

As shown in FIG. 2, the ITSAC 15 may include a traffic session admissioncontrol (TSAC) module 210, a management application module 220, a callprocessing application module 230, and a packet scheduler module 240.Exemplarily, the TSAC module 210 may provide an intelligent trafficsession admission control for admission requests from UE 14 and the bulkof this disclosure will be dedicated to explaining exemplary features ofthe TSAC module 210. The management application module 220 may allow theoperator or manager of the eNB 11 to specify certain parameters for theeNB 11 that are stored in the admission control context module 201 ofthe TSAC 210.

The call processing application module 230 may receive signaling packetsfrom the MME 13 and after performing a sanity check on the signalingpackets, the call processing application module 230 may pass on thesignaling packets to the TSAC 210 for admission control analysis andpre-emption analysis. The sanity check may involve involves doing abrief check on the ordering of mandatory parameters and examining theconsistency and evenness of the parameter values. In particular, thecall processing application module 230 may receive an E-RAB (E-UTRANRadio Access Bearer) setup message from the MME 13 and forward the E-RABsetup message to the TSAC 210. The E-RAB set up message refers to asession setup request from the MME 13 to setup a new session for the UE14, which is requesting admission to the eNB 11 so that it may transferand receive data through the eNB 11.

The packet scheduler module 240 may calculate eNB 11 specific parameterssuch as Average Packet Drop Rate (PDR) per QCI, Average Scheduling Delayper QCI, Average Throughput per QCI, and the like, where QCI stands forQuality of Service Class Identifier. QCI is a scalar value that may beassociated with the type of data to be transmitted or the type of call;for example, a certain QCI value may be assigned to a videotransmission, a different QCI value may be assigned to Voice over IP(VOIP) call, and another QCI value may be assigned to a web browsingsession. The packet scheduler module 240 may analyze the varioussessions currently supported by the eNB 11, group them by theirrespective QCIs, and calculate the Average PDR, Average SchedulingDelay, Average Throughput per QCI and the like based on the analysis.Exemplarily, the packet scheduler module 240 may calculate these valuesrepeatedly after a predetermined amount of time such as 1 ms, 2 ms, etc.Next, a detailed description of the TSAC 210 is provided.

The TSAC 210 may include an admission control context module 201, apre-emption decision module 202, a dynamic traffic session analyzermodule 203, and a traffic session setup analyzer module 204. Each ofthese modules will be explained in further detail next.

Admission Control Context Module 201

The admission control context module 201 may store parameters that areutilized by other modules of the TSAC 210 to perform admission control.The parameters stored in the admission control context module 201 may beclassified into 3 broad categories.

a. Configuration Parameters

-   -   i. Guaranteed Bit Rate (GBR) per QCI    -   ii. Maximum Throughput in Downlink direction    -   iii. Minimum Throughput per QCI    -   iv. Hysteresis Throughput per QCI    -   v. Packet Drop Rate (PDR) per QCI    -   vi. Hysteresis Packet Drop Rate per QCI    -   vii. Scheduling Delay per QCI    -   viii. Hysteresis Scheduling Delay per QCI    -   ix. Operator's priority between Highest PDR and Highest        Scheduling Interval    -   x. ITSAC Enabler

b. User Context(s)

-   -   i. QCI    -   ii. Priority Level    -   iii. Pre-emption Capability    -   iv. Pre-emption Vulnerability    -   v. GBR QoS Information

c. Global Data

-   -   i. Average Packet Drop Rate per QCI    -   ii. Average Scheduling Delay per QCI    -   iii. Average Throughput per QCI

The configuration parameters may be set by the operator of the eNB 11through management application module 220. Many of the configurationparameters (GBR per QCI, Maximum Throughput in Downlink Direction,Minimum Throughput per QCI) are well known to one of ordinary skill inthe art as they are defined in the 3GPP standard. The ITSAC Enabler is aturn on/off setting which may be set by the operator to turn ON/OFF theoperations of the ITSAC 15.

The user context parameters are E-RAB level Quality of Serviceparameters that are specific to various sessions currently administeredby the eNB 11 and these parameters are also defined in the 3GPPstandard. These E-RAB level parameters may be retrieved by trafficsession setup analyzer module 204 from the E-RAB set up messages sent byMME 13. The traffic session setup analyzer module 204 may store theseparameters in admission control context module 201. These parameters mayinclude the QCI and priority level of the session. They may also includethe “Pre-emption Capability” parameter, which indicates whether theassociated session is capable of preempting other active sessions, andthe “Pre-emption Vulnerability” parameter, which indicates if theassociated session can be preempted by other sessions. They may furtherinclude GBR Quality of Service information (GBR QoS) for the session.

The Global Data parameters (Average PDR per QCI, Average SchedulingDelay per QCI, Average Throughput per QCI) are parameters specific tothe current conditions of eNB 11 that may be calculated by packetscheduler module 240. These parameters may be analyzed by dynamictraffic session analyzer module 203 and stored in admission controlcontext module 201.

Pre-Emption Decision Module 202

The pre-emption decision module 202 may decide on a final target list ofthe eNB 11's existing session(s) which may be pre-empted for allowingadmission of the new session requested by UE 14. The pre-emptiondecision module 202 may utilize parameters such as Highest PDR, HighestScheduling Interval, and Pre-emption Vulnerability for the existingsession(s) to prepare the pre-emption list.

Dynamic Traffic Session Analyzer Module 203

The dynamic traffic session analyzer module 203 may retrieve from thepacket scheduler 240 the Global data parameters after a predeterminedamount of time (for example, 1 ms). The dynamic traffic session analyzermodule 203 may also inform call processing application module 230 topre-empt (if any) one or more of the eNB 11's existing session(s) forallowing admission of the new session requested by UE 14. The dynamictraffic session analyzer module 203 may also inform call processingapplication module 230 to allow/reject the admission of the new sessionrequested by the UE 14.

Traffic Session Setup Packet Analyzer Module 204

The traffic session setup analyzer module 204 may analyze E-RAB setupspecific messages like Initial Context Setup Request, E-RAB SetupRequest or Handover Requests coming from the EPC 12. The traffic sessionsetup analyzer module 204 may retrieve E-RAB Level QoS Parameters (UserContext parameters discussed above) from the received E-RAB setupmessages and store them in admission control context module 201.

Next, a detailed machine algorithm is presented with reference to FIGS.3A, 3B, 3C, and 3D for describing exemplary functions of ITSAC 15 forcall admission control. In S301, an E-RAB setup message may be receivedby ITSAC 15 (in eNB 11) from MME 13. The E-RAB setup message may be asession setup request message for admitting a new session associatedwith UE 14. The E-RAB setup message may be analyzed by call processingapplication module 230 and forwarded to traffic session setup analyzermodule 204.

The E-RAB setup message may include a QCI for the new session that maybe utilized by admission control context module 201 to retrieve from itsconfiguration manager (not shown) certain parameters related to the QCI.The QCI for the new session requested by UE 14 will be referredhereinafter as QCI(i). In particular, in S302, admission control contextmodule 201 may retrieve the following parameters:

a. GBR per QCI (GBR_QCI)

b. Max. Throughput in Downlink direction (TPUTmax)

c. Min. Throughput per QCI (Min_TputQCI(i)_TH)

d. Hysteresis Throughput per QCI (HYST_TPUT_QCI(i))

e. Packet Drop Rate per QCI (PktDropQCI(i)_TH)

f. Hysteresis Packet Drop Rate per QCI (HYST_PDR_QCI(i))

g. Scheduling interval per QCI (SchIntervalQCI(i)_TH)

h. Hysteresis Scheduling interval per QCI(HYST_SCH_INTERVAL_QCI(i))

The parameters TPUTmax and GBR_QCI are not specific to QCI(i) but aregeneral parameters of the eNB 11 that may be set by the operator of theeNB 11. GBR_QCI refers to a list or table of GBR values for differentQCIs.

In S303, traffic session setup analyzer module 204 may retrieve from thereceived E-RAB setup message, the following parameters for the newsession requested by UE 14:

a. QCI

b. Priority Level

c. Pre-emption Capability

d. Pre-emption Vulnerability

e. GBR QoS Information

The traffic session setup analyzer module 204 may also retrieve theabove parameters for the current/existing sessions of eNB 11 fromadmission control context module 201.

In S304, traffic session setup analyzer module 204 may retrieve thefollowing parameters from packet scheduler 240 for QCI(i):

a. Avg. Packet Drop Rate per QCI: Avg_PktDropQCI(i)

b. Avg. Scheduling interval per QCI: Avg_SchIntervalQCI(i)

c. Min. Throughput per QCI: Min_TputQCI(i)

Next, traffic session setup analyzer module 204 may determine whethereNB 11 has capacity to admit the new session. Turning now to FIG. 3B, inS305, traffic session setup analyzer module 204 may check whether GBRQoS information is present in the E-RAB setup message received from theMME for the new session. If GBR QoS information for the new session ispresent in the received E-RAB setup message traffic session setupanalyzer module 204 may map GBR QoS information to GBR_(NewFlow) (S306).However, if GBR QoS information for the new session is not present inthe received E-RAB setup message, traffic session setup analyzer module204 may utilize the QCI value of the new session (in this exemplaryembodiment QCI(i)) to look up the GBR (S307) for QCI(i) from S302.Exemplarily, traffic session setup analyzer module 204 may refer to theGBR_QCI table in admission control context module 201 to determine a GBRvalue for QCI(i) and map the same to GBR_(NewFlow).

In S308, traffic session setup analyzer module 204 may determine whethercapacity exists in eNB 11 to admit the new session by calculating a GBRThroughput Deficit (GBRTputDeficit) using the following equation:

GBRTputDeficit=TPUTmax−Σ₁ ^(n)GBR_(i)−GBR_(NewFlow)

In the above equation, TPUTmax was retrieved from admission controlcontext module 201, and n is the number of existing sessionsadministered by eNB 11. In the equation, GBR_(NewFlow) and the sum ofGBRs for existing sessions is subtracted from TPUTmax that is themaximum throughput of eNB 11 in the downlink direction.

In S309, traffic session setup analyzer module 204 may determine whetherGBRTputDeficit is a positive or negative value. A positive value wouldindicate that eNB 11 has not exhausted all of its capacity and may beable to admit the new session. A negative value would indicate that eNB11 does not have enough capacity to admit the new session and thatcertain existing sessions will have to be preempted in order to admitthe new session. How the eNB 11 or ITSAC 15 may decide whether to admitor deny the new session and which session(s) to preempt is describednext.

If in S309, traffic session setup analyzer module 204 determines thatGBRTputDeficit is a positive value, control may be passed to dynamictraffic session analyzer module 203 for further calculations to ensurethat eNB 11 is not overloaded in the QCI category for the new session.For example, if the QCI value for the new session corresponds to a videocall, dynamic traffic session analyzer module 203 may determine whethereNB 11 is servicing too many video calls that may be putting a strain onthe eNB resources. In such a scenario, where certain precautionarylimits set by the operator of the eNB 11 are being violated or would beviolated if the new session is admitted, the new session may be rejectedin spite of eNB 11 having additional capacity to admit the new session.Whether these precautionary limits are being exceeded may be checked inS321, S322, and S323 (described in further detail below).

If in S309, it is determined that GBRTputDeficit is a negative value,certain existing sessions may have to be preempted in order to admit thenew session. In S310, pre-emption decision module 202 may determinewhether the new session has the capability to preempt other sessions andif not, the new session may be rejected in S320. Whether the new sessionhas the capability to preempt other sessions may determined by checkingwhether the Pre-emption Capability flag is set for the new session inthe E-RAB level QoS parameters retrieved from the E-RAB setup messagefor the new session. If the Pre-emption Capability flag is set,pre-emption decision module 202 may determine that the new session haspre-emption capability and control may proceed to S311.

Turning now to FIG. 3C, in S311, pre-emption decision module 202 maybuild a set ‘S’ of all existing sessions of eNB 11 that have the sameQCI value as the new session, i.e., QCI(i), and whose priority level(see 2b in S303) is lower than the priority level of the new session.The priority level of the new session was previously retrieved bytraffic session setup analyzer module 204 in S303 and the priority levelof existing sessions having QCI(i) may be retrieved from admissioncontrol context module 201.

In S312, pre-emption decision module 202 may determine whether the set‘S’ is null. If ‘S’ is null, pre-emption decision module 202 may informcall processing application module 230 to reject the new session (S320)(See FIG. 3D). If ‘S’ is not null, pre-emption decision module 202 maydetermine sessions in set ‘S’ whose Pre-emption Vulnerability flag isset and add those sessions to a viable set (S313). As discussed earlier,the Pre-emption Vulnerability flag indicates whether a particularsession can be preempted. In S314, pre-emption decision module 202 maydetermine whether the viable set is null. If the viable set isdetermined to be null, pre-emption decision module 202 may inform callprocessing application module 230 to reject the new session (S320). Ifthe viable set is not null in S314, processing may continue to S315.

In S315, pre-emption decision module 202 may determine for the sessionsin the viable set the session with the highest PDR and highestscheduling interval. The PDR and scheduling intervals for each of thesessions may be obtained from packet scheduler module 240, admissioncontrol context module 201, or another database where such informationmay be stored. A scheduling interval may refer to the time taken betweentwo successive scheduling decisions of a flow, where flow in turn refersto a call or session with some associated QCI. In certain exemplaryembodiments, one or both the PDR and scheduling intervals may beobtained.

In S316, pre-emption decision module 202 may check if there exists asession ‘F’ in the viable set that has both the highest PDR and thehighest scheduling interval from among all the sessions in the viableset. If such a session exists, the session ‘F’ may be selected forfurther processing in S318 (See FIG. 3D). If pre-emption decision module202 determines in S316 that such a session does not exist, pre-emptiondecision module 202 may select in S317 a session ‘F’ from the viable setthat has the highest PDR or the highest scheduling interval andprocessing may continue to S318. Whether to select a session withhighest PDR or to select a session with highest scheduling interval maybe based on a preference set by the operator of the eNB 11.

Turning now to FIG. 3D, in S318 pre-emption decision module 202 mayremove the session ‘F’ from the viable set, add the selected session ‘F’to a preemption set, and determine the effect of preempting the session‘F’ on the available capacity of eNB 11. For example, pre-emptiondecision module 202 may obtain the GBR QoS for flow ‘F’ from admissioncontrol context module 201 and add it to GBRTputDeficit calculated inS308 to obtain an updated GBRTputDeficit. In S319, pre-emption decisionmodule 202 may check whether the updated GBRTputDeficit is greater thanzero. If the updated GBRTputDeficit is not greater than zero,pre-emption decision module 202 may decide to add additional sessions‘F’ from the viable set to the preemption set until the updatedGBRTputDeficit becomes greater than zero. To add additional sessions‘F,’ pre-emption decision module 202 may return to S314 and processS314-S319 again by picking another session in the viable set.

Turning back to FIG. 3C, once pre-emption decision module 202 determinesa preemption set, which if preempted, may provide sufficient additionalcapacity to eNB 11 to admit the new session, pre-emption decision module202 may provide the preemption set to dynamic traffic session analyzermodule 203 for further processing in S321-S323. In certain exemplaryembodiments, however, pre-emption decision module 202 may provide thepreemption set to the call processing application module 230, which maypreempt the sessions in the preemption set and admit the new sessionwithout dynamic traffic session analyzer module 203 processing S321-323.That is, in certain exemplary embodiments, S321-S323 may not be carriedout once a preemption set is determined by pre-emption decision module202.

In S321-S323, dynamic traffic session analyzer module 203 may determinewhether current performance in eNB 11 for sessions with QCI(i) isacceptable according to certain predetermined criteria. Exemplarily, thepredetermined criteria may be defined by the operator of eNB 11.Examples of predetermined criteria may be found in S321-S323. Onecriteria may be whether minimum throughput (Min_TputQCI(i)) for sessionswith QCI(i) is greater than the sum of a threshold minimum throughput(Min_TputQCI(i)_TH) for QCI(i) set by the operator and a hysteresisvalue (HYST_TPUT_QCI(i)) for QCI(i) set by the operator. Other criteriamay be whether the current average scheduling interval(Avg_SchIntervalQCI(i)) for QCI(i) as determined by packet schedulermodule 240 is less than the sum of a threshold scheduling interval(SchIntervalQCI(i)_TH) for QCI(i) set by the operator and a hysteresisvalue (HYST_SCH_INTERVAL_QCI(i)) for QCI(i). Another criteria may bewhether the current average packet drop rate for sessions with QCI(i) asdetermined by packet scheduler module 240 is less than the sum of athreshold packet drop rate (PktDropQCI(i)_TH) for QCI(i) set by theoperator and a hysteresis value (HYST_PDR_QCI(i)) for QCI(i).

Exemplarily, dynamic traffic session analyzer module 203 may check oneor more of the above criteria in S321-S323 and if the criteria are foundto be not satisfied, dynamic traffic session analyzer module 203 mayinform call processing application module 230 to reject the new sessionin spite of the presence of a list of sessions in the preemption setthat can be preempted. It will be noted that the order of S321-S323 isonly provided as an example and in certain exemplary embodiments, theorder of S321-S323 may be changed as may the order of any steps shown inFIGS. 3A-3D.

If the criteria in S321-S323 is satisfied, dynamic traffic sessionanalyzer module 203 may inform call processing application module 230 topreempt the sessions in the preemption set in S324 and admit the newsession in S325. Following these steps, control may return to S301 oranother intermediate step such as S302 for processing a request to admitanother new session.

While an exemplary machine algorithm has been described with referenceto FIGS. 3A, 3B, 3C, and 3D, it will be understood that certainexemplary embodiments may change the order of steps in the machinealgorithm or may even eliminate or modify certain steps. For example, anexemplary embodiment may modify S315 to check only one of the highestPDR and highest scheduling interval. In another exemplary embodiment,S313 and S314 may be eliminated such that control directly proceeds fromS312 to S315 with the set ‘S’ utilized as the viable set. Othervariations to the exemplary machine algorithm set forth in FIGS. 3A-3Dwill be apparent to a skilled artisan.

FIGS. 4A, 4B, 4C, and 4D describe another exemplary embodiment of theITSAC 15. In particular, FIGS. 4A-4D describe a variation of theexemplary embodiment set forth with respect to FIGS. 3A-3D andtherefore, an explanation of the common elements between these twoembodiments is omitted in the interest of conciseness. Rather, FIGS.4A-4D are explained by describing exemplary differences between FIGS.4A-4D. An exemplary difference between FIGS. 3A-3D and FIGS. 4A-4D isthat in FIGS. 3A-3D, dynamic traffic session analyzer module 203 maydetermine whether current performance in eNB 11 for sessions with QCI(i)is acceptable by checking the predetermined criteria in S321, S322, andS323, whereas in FIGS. 4A-4D, dynamic traffic session analyzer module203 may determine whether current performance in eNB 11 for sessionswith QCI(i) is acceptable by checking only S321. Exemplarily, thecriteria checked in S321 may be whether minimum throughput(Min_TputQCI(i)) for sessions with QCI(i) is greater than the sum of athreshold minimum throughput (Min_TputQCI(i)_TH) for QCI(i) set by theoperator and a hysteresis value (HYST_TPUT_QCI(i)) for QCI(i) set by theoperator. If the criteria in S321 is satisfied, dynamic traffic sessionanalyzer module 203 may inform call processing application module 230 topreempt the sessions in the preemption set in S324 and admit the newsession in S325. Following these steps, control may return to S301 oranother intermediate step such as S302 for processing a request to admitanother new session.

FIGS. 5A, 5B, 5C, and 5D describe yet another exemplary embodiment forthe ITSAC 15. In particular, FIGS. 5A-5D also describe a variation ofthe exemplary embodiment set forth with respect to FIGS. 3A-3D andtherefore, an explanation of the common elements between these twoembodiments is omitted in the interest of conciseness. Rather, FIGS.5A-5D are explained by describing exemplary differences between FIGS.3A-3D. An exemplary difference between FIGS. 3A-3D and FIGS. 5A-5D isthat in FIGS. 3A-3D, dynamic traffic session analyzer module 203 maydetermine whether current performance in eNB 11 for sessions with QCI(i)is acceptable by checking the predetermined criteria in S321, S322, andS323, whereas in FIGS. 5A-5D, dynamic traffic session analyzer module203 may determine whether current performance in eNB 11 for sessionswith QCI(i) is acceptable by checking only S322. Exemplarily, dynamictraffic session analyzer module 203 may check whether the currentaverage scheduling interval (Avg_SchIntervalQCI(i)) for QCI(i) asdetermined by packet scheduler module 240 is less than the sum of athreshold scheduling interval (SchIntervalQCI(i)_TH) for QCI(i) set bythe operator and a hysteresis value (HYST_SCH_INTERVAL_QCI(i)) forQCI(i). If the criteria in S322 is satisfied, dynamic traffic sessionanalyzer module 203 may inform call processing application module 230 topreempt the sessions in the preemption set in S324 and admit the newsession in S325. Following these steps, control may return to S301 oranother intermediate step such as S302 for processing a request to admitanother new session.

FIGS. 6A, 6B, 6C, and 6D describe yet another exemplary embodiment forthe ITSAC 15. In particular, FIGS. 6A-6D also describe a variation ofthe exemplary embodiment set forth with respect to FIGS. 3A-3D andtherefore, an explanation of the common elements between these twoembodiments is omitted in the interest of conciseness. Rather, FIGS.6A-6D are explained by describing exemplary differences between FIGS.3A-3D. An exemplary difference between FIGS. 3A-3D and FIGS. 6A-6D isthat in FIGS. 3A-3D, dynamic traffic session analyzer module 203 maydetermine whether current performance in eNB 11 for sessions with QCI(i)is acceptable by checking the predetermined criteria in S321, S322, andS323, whereas in FIGS. 6A-6D, dynamic traffic session analyzer module203 may determine whether current performance in eNB 11 for sessionswith QCI(i) is acceptable by checking only S323. Exemplarily, dynamictraffic session analyzer module 203 may check whether the currentaverage packet drop rate for sessions with QCI(i) as determined bypacket scheduler module 240 is less than the sum of a threshold packetdrop rate (PktDropQCI(i)_TH) for QCI(i) set by the operator and ahysteresis value (HYST_PDR_QCI(i)) for QCI(i). If the criteria in S323is satisfied, dynamic traffic session analyzer module 203 may informcall processing application module 230 to preempt the sessions in thepreemption set in S324 and admit the new session in S325. Followingthese steps, control may return to S301 or another intermediate stepsuch as S302 for processing a request to admit another new session.

While FIGS. 3A-6D illustrate exemplary embodiments where a dynamictraffic session analyzer module 203 may determine whether currentperformance in eNB 11 for sessions with QCI(i) is acceptable by checkingthe predetermined criteria in one of or all of S321, S322, and S323,embodiments consistent with the present invention may check anycombination of the predetermined criteria in steps S321, S322, and S323.For example, the analyzer module 203 may check the predeterminedcriteria in S321 and S323. As another example, the analyzer module maycheck the predetermined criteria in S322 and S323. Other variations tothe exemplary machine algorithms set forth in FIGS. 3A-6D will also beapparent to a skilled artisan.

The different components of ITSAC 15 (FIG. 2) may be embodied inhardware or software or a combination of both. The hardware may includea general-purpose computer having a central processing unit (CPU) andmemory/storage devices that store data and various programs such as anoperating system and one or more application programs. Furthermore, eachof the steps in the machine algorithms described in FIGS. 3A-6D may beembodied as computer-readable instructions or code and stored in anon-transitory computer-readable storage medium for execution by acomputer.

Other embodiments of the present disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the embodiments disclosed herein. It is intended that thespecification and examples be considered as exemplary only, with a truescope and spirit of the disclosure being indicated by the followingclaims.

What is claimed is:
 1. A method of providing session admission controlfor a new session in a broadband wireless network, the methodcomprising: obtaining a guaranteed bit rate and a first quality ofservice class indicator for the new session; calculating an availablecapacity using the guaranteed bit rate; determining whether theavailable capacity is a negative or a positive value; in response to theavailable capacity being a negative value, selectively searching throughexisting sessions for a first session to be preempted; in response tothe available capacity being a positive value, determining a firstplurality of sessions from among the existing sessions that have thefirst quality of service class indicator and checking whetherperformance metrics for the first plurality of existing sessions satisfypredetermined criteria; and admitting or rejecting the new session. 2.The method of claim 1, wherein determining whether performance metricsfor the first plurality of existing sessions having the first quality ofservice class indicator satisfy predetermined criteria includes:checking whether minimum throughput for the first plurality of existingsessions exceeds a sum of a threshold minimum throughput and ahysteresis value; and rejecting the new session in response to theminimum throughput exceeding the sum.
 3. The method of claim 1, whereindetermining whether performance metrics for the first plurality ofexisting sessions having the first quality of service class indicatorsatisfy predetermined criteria includes: checking whether a currentaverage scheduling interval is lower than a sum of a thresholdscheduling interval and a hysteresis value; and rejecting the newsession in response to the current average scheduling interval beinglower than the sum.
 4. The method of claim 1, wherein determiningwhether performance metrics for the first plurality of existing sessionshaving the first quality of service class indicator satisfypredetermined criteria includes: checking whether a current averagepacket drop rate is lower than a sum of a threshold packet drop rate anda hysteresis value; and rejecting the new session in response to thecurrent average packet drop rate being lower than the sum.
 5. The methodof claim 1, wherein selectively searching through existing sessions fora first session includes: determining whether a pre-emption capabilityflag is set for the new session; rejecting the new session in responseto the pre-emption capability flag not being set; and in response to thepre-emption capability flag being set, searching through the existingsessions for a second plurality of existing sessions having the firstquality of service class indicator and a priority level lower than apriority level for the new session.
 6. The method of claim 5, furthercomprising: selecting the first session to be preempted from the secondplurality of existing sessions; and determining whether preempting thefirst session will result in the available capacity becoming a positivevalue.
 7. The method of claim 6, further comprising: in response todetermining that preempting the first session will result in theavailable capacity becoming a positive value, checking whetherperformance metrics for the first plurality of existing sessions satisfypredetermined criteria.
 8. The method of claim 7, wherein checkingwhether performance metrics for the first plurality of existing sessionshaving the first quality of service class indicator satisfypredetermined criteria includes: checking whether a current averagescheduling interval is lower than a sum of a threshold schedulinginterval and a hysteresis value; and rejecting the new session inresponse to the current average scheduling interval being lower than thesum.
 9. The method of claim 7, wherein checking whether performancemetrics for the first plurality of existing sessions having the firstquality of service class indicator satisfy predetermined criteriaincludes: checking whether a current average packet drop rate is lowerthan a sum of a threshold packet drop rate and a hysteresis value; andrejecting the new session in response to the current average packet droprate being lower than the sum.
 10. The method of claim 7, whereinchecking whether performance metrics for the first plurality of existingsessions having the first quality of service class indicator satisfypredetermined criteria includes: checking whether minimum throughput forthe first plurality of existing sessions exceeds a sum of a thresholdminimum throughput and a hysteresis value; and rejecting the new sessionin response to the minimum throughput exceeding the sum.
 11. A systemfor implementing session admission control for a new session in abroadband wireless network, the system comprising: a hardware processor;and a memory storing instructions for execution by the hardwareprocessor, wherein the hardware processor is configured by theinstructions to: obtain a guaranteed bit rate and a first quality ofservice class indicator for the new session; calculate an availablecapacity using the guaranteed bit rate; determine whether the availablecapacity is a negative or a positive value; in response to the availablecapacity being a negative value, selectively search through existingsessions for a first session to be preempted; in response to theavailable capacity being a positive value, determine a first pluralityof sessions from among the existing sessions that have the first qualityof service class indicator and check whether performance metrics for thefirst plurality of existing sessions satisfy predetermined criteria; andadmit or reject the new session.
 12. The system of claim 11, whereindetermining whether performance metrics for the first plurality ofexisting sessions having the first quality of service class indicatorsatisfy predetermined criteria includes: checking whether minimumthroughput for the first plurality of existing sessions exceeds a sum ofa threshold minimum throughput and a hysteresis value; and rejecting thenew session in response to the minimum throughput exceeding the sum. 13.The system of claim 11, wherein determining whether performance metricsfor the first plurality of existing sessions having the first quality ofservice class indicator satisfy predetermined criteria includes:checking whether a current average scheduling interval is lower than asum of a threshold scheduling interval and a hysteresis value; andrejecting the new session in response to the current average schedulinginterval being lower than the sum.
 14. The system of claim 11, whereindetermining whether performance metrics for the first plurality ofexisting sessions having the first quality of service class indicatorsatisfy predetermined criteria includes: checking whether a currentaverage packet drop rate is lower than a sum of a threshold packet droprate and a hysteresis value; and rejecting the new session in responseto the current average packet drop rate being lower than the sum. 15.The system of claim 11, wherein selectively searching through existingsessions for a first session includes: determining whether a pre-emptioncapability flag is set for the new session; rejecting the new session inresponse to the pre-emption capability flag not being set; and inresponse to the pre-emption capability flag being set, searching throughthe existing sessions for a second plurality of existing sessions havingthe first quality of service class indicator and a priority level lowerthan a priority level for the new session.
 16. The system of claim 15,wherein the hardware processor is further configured by the instructionsto: select the first session to be preempted from the second pluralityof existing sessions; and determine whether preempting the first sessionwill result in the available capacity becoming a positive value.
 17. Thesystem of claim 16, wherein the hardware processor is further configuredby the instructions to: in response to determining that preempting thefirst session will result in the available capacity becoming a positivevalue, checking whether performance metrics for the first plurality ofexisting sessions satisfy predetermined criteria.
 18. The system ofclaim 17, wherein checking whether performance metrics for the firstplurality of existing sessions having the first quality of service classindicator satisfy predetermined criteria includes: checking whether acurrent average scheduling interval is lower than a sum of a thresholdscheduling interval and a hysteresis value; and rejecting the newsession in response to the current average scheduling interval beinglower than the sum.
 19. The system of claim 17, wherein checking whetherperformance metrics for the first plurality of existing sessions havingthe first quality of service class indicator satisfy predeterminedcriteria includes: checking whether a current average packet drop rateis lower than a sum of a threshold packet drop rate and a hysteresisvalue; and rejecting the new session in response to the current averagepacket drop rate being lower than the sum.
 20. The system of claim 17,wherein checking whether performance metrics for the first plurality ofexisting sessions having the first quality of service class indicatorsatisfy predetermined criteria includes: checking whether minimumthroughput for the first plurality of existing sessions exceeds a sum ofa threshold minimum throughput and a hysteresis value; and rejecting thenew session in response to the minimum throughput exceeding the sum.